mysql-test/r/variables.result:
  new test
mysql-test/t/ctype_utf8.test:
  typos fixed
mysql-test/t/variables.test:
  new test
sql/mysqld.cc:
  sys_str_var->value must be not NULL
sql/set_var.cc:
  initialize sys_str_var->value from a constructor
sql/set_var.h:
  initialize sys_str_var->value from a constructor